1. Field of the Invention
The invention relates generally to printing ink compositions and specifically to methods for producing printing ink compositions comprising basic potassium aluminum sulfate (BKAS) and/or basic sodium aluminum sulfate (BNaAS) as a pigment or filler.
2. Description of the Prior Art
Various inorganic compounds are used in printing inks as opacifying pigments including titanium dioxide, calcium carbonate, clay, zinc oxide, baryte, barium sulfate, aluminum hydrate, talc, silica, etc. Such are also conventionally used as extender pigments in printing inks. But these materials vary in cost, opacity, and pH stability, when used in printing inks.
Many of the inorganic materials used as filler and colorants in printing inks are mined. So the particle size, its size distribution, and the surface chemistry and physics are hard to control without post-mining treatments that can add significant cost.